expansion valve problem
We have a situation with a water to water heat pump.
If the bulb of the expansion valve is stick to the pipe , after 30 sec is closing the flow and the pressure goes up (at 20 C is reaching 2.5 mpa)
If we remove it from the pipe, and is not regulating the flow, the heat pumps works perfect.
It is a thermal expansion valve from Emerson ....
are you sure everything is positioned properly & your charge is
Is it a water furnace? They had a bad batch of TXV's that when out. It sounds like the TXV has lost some of its head charge.